Treatment of automotive industry wastewater by electrocoagulation using commercial aluminum electrodes

Abstract

Industrial liquid wastes may cause serious damage to nature and human health. Taking into account the protection of water resources and, especially, compliance to current legislation and international standards, several technologies for wastewater treatment have been studied. In general, the physico-chemical treatment is well-established and is applied by most industries. Electrocoagulation (EC) is a wastewater treatment method that has been evaluated as a procedure that may replace conventional treatment and significantly reduce the amount of sludge produced. Within this context, this work aimed to apply EC to the treatment of an industrial liquid waste from an automotive company to assess the efficiency of the technique. The industrial wastewater was collected, treated, and analyzed with regard to some discharge standards, including phosphorus, oils and greases, pH, turbidity, and metals (Al, Cr, Fe, Mn, and Zn). Moreover, the wear of aluminum electrodes used in the process, the electricity consumption, and compliance with the discharge standards were also evaluated. In general, either the removal efficiency or the reduction of discharge parameters was proportional to time and electric current density, but only one set of applied parameters met all limits. Electric current efficiencies exceeded 150 %, indicating that the wear of electrodes surpassed the estimate provided by Faraday’s law. In addition, the electricity consumption increased proportionally to the time and electric current density with a loss of energy as heat.